The most difficult calendar riddles A list of calendar related questions that are most often answered incorrectly Mathematics quiz What is the meaning of the word "December", adopted from Latin by most of European languages?Tenth month. Originally Roman calendar was comprised only of 10 months. December was the 10th and last of them. Eventually a calendar reform introduced January and February, but preserved the ordinal naming convention of the older months.very hard 35% twelve monthtwelve month23%tenth monthtenth month35%last month of a yearlast month of a year23%cold monthcold month17%Created by: smyru. Statistics based on 2400 answers in 2 languages »history of Europe riddles » If there is Friday 13th in a month, then ...This month starts on Sunday. If 1 is Sunday then Friday is on 6th and 13th. The length of month may vary.very hard 36% this month has 30 or 31 daysthis month has 30 or 31 days9%this month starts on Sundaythis month starts on Sunday36%this month ends on Sundaythis month ends on Sunday11%All of the answers are correctAll of the answers are correct43%Created by: lukasz Poland. Statistics based on 760 answers in 2 languages »legends riddles » Augustus was born on 1 January 10BC. Which birthday did he celebrate at 1 January 10AD?19. There was no year number zero. There were only 1999 years between 1000BC and 1000AD.very hard 38% 191938%202037%212119%80805%Created by: Gizem İsmailoğlu. Statistics based on 18629 answers in 5 languages »math riddles » Typically, how many leap years are in a century?24. The Gregorian Calendar omits 3 leap days every 400 years, omitting February 29 in the 3 century years (integer multiples of 100) that are not also integer multiples of 400. For example, 1600 was a leap year, but 1700, 1800 and 1900 were not. Similarly, 2000 was a leap year, but 2100, 2200, and 2300 will not be.hard 42% 20209%242442%252544%1001004%Created by: ex-terminator. Statistics based on 16433 answers in 2 languages »numbers riddles » How many times in year can Friday 13th happen?Up to 3. Friday 13th can happen three times in in year when: year starts on Thursday or (leap year) on Sunday. hard 47% up to 2up to 223%up to 3up to 347%up to 4up to 421%up to 5up to 58%Created by: lukasz Poland. Statistics based on 1098 answers in 2 languages »author: lukasz Poland riddles » How many months have 31 days in them?7. January, March, May, July, August, October and December.hard 57% 5513%6616%7757%8812%Created by: Kasia. Statistics based on 17336 answers in 2 languages »mathematics riddles » Which country started using 7 days in week?Babylon. The seven-day week has deep historical origins in the astrology of Ancient Near East, being approximately a quarter of a lunation. It was (independently) adopted by the Persian Empire, in Judaism and in Hellenistic astrology, and (via Greek transmission) in Gupta India and Tang China.hard 57% Ancient GreeceAncient Greece18%Ancient EgyptAncient Egypt15%Ancient IndiaAncient India8%BabylonBabylon57%Created by: $#O!@B. Statistics based on 4742 answers in 2 languages »history riddles » Which day was the last of the 20th century?31 Dec 2000. There was no year number zero. So, the first century started on 1 Jan 1. Similarly, 21th century started 1 Jan 2001.average 65% 31 Dec 199931 Dec 199925%31 Dec 200031 Dec 200065%31 Dec 200131 Dec 20015%31 Dec 189931 Dec 18992%Created by: Jason Beagley. Statistics based on 22438 answers in 3 languages »time riddles » Who introduced the Gregorian calendar?Pope Gregory XIII. Gregory XIII was pope during the period from 13 May 1572 until 10 April 1585. The Gregorian calendar, also called the Western Calendar, was introduced by him in 1582 with the Bull Inter Gravissimas. The gregorian calendar basically a refinement of the Julian calendar. The Gregorian reform modified the Julian calendar's scheme of leap years, changing the mean length of the calendar year from 365.25 days to 365.2425 days.easy 70% Pope Gregory I, called the GreatPope Gregory I, called the Great17%St. Gregory the IlluminatorSt. Gregory the Illuminator4%Pope Gregory XIIIPope Gregory XIII70%GalileoGalileo7%Created by: Krzysztof Moskal. Statistics based on 15536 answers in 3 languages »popes riddles » Play mathematics quiz and see all the questions.